Active speaker identification

ABSTRACT

Procedures for identifying clients in an audio event are described. In an example, a media server may order clients providing audio based on the input level. An identifier may be associated with the client for identifying the client providing input within the event. The ordered clients may be included in a list which may be inserted into a packet header carrying the audio content.

BACKGROUND

Media conference participants may have difficulty identifying otherconference participants. A participant may be unfamiliar with aspeaker's voice or a participant's face or the audio exchange mayconfuse a listener. In the latter case, a listener, whether speaking ornot, may be confused if several participants are speaking concurrentlyor if there is a rapid exchange between multiple participants. In somecases, speakers may include his/her name “[t]his is Bob, . . .” or alistener may ask the identity of a previous speaker. The complexity ofthis issue may increase as the number of participants speaking, orcontributing audio input, increases. While a listener may derive thespeaker's identity from “context clues” within the conversation, in someinstances, participants may not comprehend which participants areproviding audio input.

Additionally, minimizing bandwidth consumption, or the amount of datathroughput for carrying information, may be desirable. For example,while a physical connection for transporting data may have additionalthroughput, consuming communication link resources may reduce thethroughput available for other data transfers, or may impact conferenceaudio data transfer if a user happens to have limited network bandwidth.

Acceptance of media conference improvements may be limited if theimprovement is not “backwards compatible.” For example, if amodification is inconsistent with existing protocols and versions, usersmay have to obtain an updated version to communicate with a participantimplementing the modified version and/or seek organizations approval.The foregoing situation may inhibit acceptance of the modifiedtechnology.

SUMMARY

Procedures for identifying clients in an audio or audio/video event aredescribed. In an example, a media server may order clients providingaudio based on the input level. An identifier may be associated with theclient for identifying the client providing input within the event. Theordered clients may be included in a list which may be inserted into apacket header carrying the audio content.

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description is described with reference to the accompanyingfigures. In the figures, the left-most digit(s) of a reference numberidentifies the figure in which the reference number first appears. Theuse of the same reference numbers in different instances in thedescription and the figures may indicate similar or identical items.

FIG. 1 illustrates an environment in an exemplary implementation thatmay use technologies to permit active speaker identification.

FIG. 2 is a diagram depicting a real-time protocol data packet includingordered/re-ordered active clients list in list of contributing sources(CSRC) field.

FIG. 3 is a flow diagram depicting a procedure in an exemplaryimplementation for identifying active clients.

FIG. 4 is a flow diagram depicting a procedure in an exemplaryimplementation for identifying active clients in a real-time protocolconference.

DETAILED DESCRIPTION

Overview

Techniques are described to identify active audio contributors in amedia event. In implementations, a list of contributing or participatingaudio clients may be arranged based on the client contribution to thesession. An identifier may be associated with the participating clientsso that clients may identify which client(s) are actively contributingto the event. The arranged list may be inserted into data stream packetheaders for forwarding to conference clients. In implementations, theidentification information may be included in control packets used inconjunction with data transport. The techniques discussed herein mayprovide speaker information while consuming minimum network resourcesand without raising synchronization issues.

In further implementations, a media server for switching/mixing audiostreams may be configured to insert an ordered list of active clientsinto data packet headers. For example, the media server may include alist of active speakers which may be ordered based on current activespeaker, such that clients are provided with information regarding whichclients are actively speaking. The list may be provided withoutincreasing the media transport overhead for a network.

Exemplary Environment

FIG. 1 illustrates environment 100 in exemplary implementations that areoperable to use active speaker identification. For example, a mediaserver 102 may identify active audio clients while mixing and switchingbetween client provided audio streams in a media event. While audio datahanding is discussed, the media server 102 may handle other type ofmedia data including video and so on, based on the conference and thecapabilities of the client devices. For example, the media server 102may manipulate audio/video data for some clients, while forwarding,audio data to clients lacking video capability and so on.

For example, a media server processor 104 may determine which client orclients are actively contributing audio content while mixing/switchingaudio streams for clients. The media server processor 104 may determinewhich clients are actively inputting audio data based on themixing/switching algorithm/techniques employed by the processor forgenerating send media streams. The determination may be used to order alist of clients contributing to outbound media streams from the mediaserver 102, or which clients contributed to the media server output.

For an audio event including Clients “A” 106, “B” 108, “C” 110, “D” 112and “E” 114 in which Clients “A” 106 and “E” 114 are contributing audioinput (such as Clients A 106 and E 114 are carrying on a conversation),non-active Clients “B” 108, “C” 110, “D” 112 may be provided with the“A+E” send stream from the media server 102, or a combination of the twospeakers, while Clients “A” 106 and “E” 114 respectively receive theopposite party send stream from the media server 102 (e.g., Client A 106receives a Client E send stream while Client E 114 receives the Client Asend stream). Suitable client devices include, but are not limited to,voice over internet protocol (VoIP) phones, computing device havingaudio capability, publicly switched network telephones (PSTN) phonesconnected through a gateway to the digital audio session, and so on.

In some implementations, active speakers may not be provided with asignal including the speaker's own send stream to avoid feedback or anecho (e.g., Client A 106 may not be sent an audio stream containingClient A audio). Several general identification scenarios may beconsidered, for example, Client A may be “talking over” Client E (suchas if the participant associated with Client A 106 is speaking loudlywhile Participant “E” (associated with Client E 114) is speaking in acomparatively normal voice), Participants “A” and “E” are engaged in aquick exchange in which the current speaker changes between the twoparticipants, or Participant “A” predominates the conversation whileParticipant “E” provides relatively less input. An example of the lattersituation may include a participant who adds minor acknowledgements tothe primary speaker's prevailing soliloquy.

In implementations, the media server 102 may determine the dominantclient (and thus a speaker) based on the number of packets received fromthe client, when audio content is received, packet size, energy audiolevel and so on. Thus, while two or more clients are contributingcontent contemporaneously, one active client may be assigned as thedominant client (and thus a speaker) based on the foregoing factors. Forexample, the media server 102 may determine the current active client(and associated speaker) based on the current data packets, includingthe audio content received from the active client in conjunction withmixing and/or switching between the inputs received from differentclients. For instance, the media server 102 may designate Client A 106as the current “active” client, if Client E is not presentlycontributing data packets. In other instances, if both Client A 106 andClient E 114 are active, but Client A 106 is contributing audio contentwith a greater energy level than Client E 114 (i.e., participant A isspeaking loudly while E is speaking in a lower tone), Client A 106 maybe assigned as the dominant active speaker. Clients may be provided withan active client list which commences with Client A 106. This type ofdetermination may be made when mixing/switching client input audiostreams for one or more ongoing conferences. For example, the mediaserver 102 processor may differentiate between the active clients whenemploying a mixing algorithm, while an identification module 116 may beused to insert the information in the applicable data packets.

With general reference to FIG. 2, in implementations, when implementingreal-time transport protocol (RTP) and associated real-time controlprotocol (RTCP), the media server 102 may identify active clients, andthus active speakers, by examining data within the streams sent from theclients, including data transport and signaling streams. In the case ofClient A 106, the media server 102 may identify that the audio clientsend stream is originating from Client A 106 by examining thesynchronization source (SSRC) field within the RTP packet or from theClient SSRC (an identifier for the client within the session) and thecanonical name (CNAME) included in the RTCP report. Other informationmay be examined as well. The SSRC also may be obtained from the RTPpacket header. For example, the SSRC may be mapped to the CNAME in aRTCP report.

While RTCP signaling may be used to identify missing packets, insuredata transport quality and so on, a RTCP report may be obtained from theRTCP out-of-band signals. For example, the RTCP report may include therandomly generated client SSRC mapped to a client CNAME. A CNAMEgenerally is an identifier/record which is associated with the aliasesused for the client device. In some instances, the CNAME is a string ofnumbers or the like. In implementations, the media server 102 may beassigned a SSRC within the session. In some instances, the SSRC maychange for a client included in a session. For example, a client SSRCmay change if a client cuts-off (e.g., a long pause and then rejoins),if client SSRCs collide (more than one client is issued a common SSRC)and so on. In this manner, an incoming data stream may be identifiedfrom the SSRC in the data stream or from the RTCP signaling. The mediaserver 102 may also obtain the canonical name from the RTCP signalingfor use in identifying the client.

When generating a send stream (including audio output), the media server102 may identify which clients are contributing audio input to thesession from the SSRC and the CNAME obtained from the active client. Forexample, the media server 102 may associate the SSRC, the CNAME insertedinto the RTCP packet, with the audio content send stream (i.e., themedia server output stream(s) carrying the audio data). Returning to theprevious example session between Clients “A” 106, “B” 108, “C” 110, “D”112 and “E” 114, in the case of the mixed signal “A+E”, the media server102 may order Clients “A” and “E” according to which client is presentlyactive, which one is active and dominating the session, or the like. Theorder may be varied based on the client providing the audio input. Inthis case, the list may start with an identifier for Client A 106 andinclude Client E 114, if Client A is currently providing input, or ifClient A dominates the conversation. In situations in which there is anaudio exchange between Client A 106 and Client E 114, the order may bechanged based on the participant currently speaking, as indicated on aper packet basis.

Referring to FIG. 2, in a RTP configuration, the media serveridentification module 116 may insert the ordered list of SSRCs in theoutput stream RTP packet header. For example, the ordered identifiersare inserted in the list of contributing sources (CSRC) field 204 in thepacket header sent in the data stream. If Client A and Client E areexchanging current active roles, the arrangement of SSRC may change from“Client A, Client E . . . ” 204(a) to “Client E, Client A . . . ”204(b). In the previous fashion, the clients receiving the data stream(listening clients or participants in the session) may be apprised as towhich clients are providing input, the relative contributions, and so onwhile avoiding additional signaling, associated synchronization issuesand network overhead. For instance, the CSRC filed may be permitted toinclude up to fifteen identifiers of thirty-two bits apiece whileremaining in conformance with the specification. Clients not performingin conformance with the techniques discussed herein may participatewithout the benefits discussed herein. Thus, making the system andtechniques backwards compatible.

While the SSRC may identify the active client, using an SSRC may beproblematic as a SSRC may be randomly assigned, may change due to acollision with another client having a similar SSRC, the client beingreassigned an SSRC after dropping out of a session and then rejoiningthe session and so on.

The media server 102 may insert the active client CNAME (s) in the RTCPpackets forwarded to the clients (e.g., so the other “listening” clientsmay be made aware of the active client CNAME and SSRC). For instance,the media server identification module 116 may “fan-out” the activeclient identifiers sent to the “listening clients” in the media serverRTCP packets. For example, if several active clients are contributing toa conference, the media server may insert the obtained clientidentifiers at designated intervals in the RTCP packets sent inconjunction with the media server data stream. While RTCP packets mayinclude the CNAME within each packet. The CNAME(s) may be interspersedin the RTCP packets forwarded to the listening clients to minimizetransport overhead. The clients receiving the media server RTCP data,including the active client identifiers, may store the data in localmemory so that the CNAME may be associated with the data packets as theaudio content is received. For example, the CNAME, the mapped SSRC andother related information may be stored in a look-up table or the like.For example, while audio content included in the data stream may be sentin a generally continuous manner, RTCP signaling may occur onlyintermittently, such as, at specified intervals (e.g., at 5 or 10 secondintervals). Thus, a client receiving a data packet may associate a SSRCin the CSRC with a previously received CNAME. In implementations, aglobally routable user agent universal resource indicator (GRUU) may beused for identifying a particular client.

In implementations, an active client may be informed that the client isthe one active in the conference. For example, the participant(associated with an active client) may desire to know that he/she is not“talking over” another participant. Returning to the session betweenClient “A” 106, “B” 108, “C” 110, “D” 112 and “E” 114, if for example,Client A 106 is active but Clients “B” 108, “C” 110, “D” 112 and “E” 114are not active, this may be identified via the RTCP signal forwarded toClient A. Thus, while the media server 102 may generate a send mediastream for Clients “B”, “C”, “D” and “E” by passing through the Client Asend stream, Client A 106 may identify that no other client is activebased on the CSRC/RTCP packets as a “listening” client or a member ofthe session.

In further implementations, human understandable information may beassociated with the SSRC and CNAME. For example, a user may desire thata picture of the speaking participant be displayed on an associatedmonitor when that participant is speaking. In implementations, humancomprehendible client information may be exchanged between clients. Forexample, the data may be exchanged generally at the beginning of anevent or session.

While the Internet (the World Wide Web) may be used for connectingclients and other components, other networks and various links aresuitable as well. For example, a network connecting the media server 102to a client may include a wide area network (WAN), a local area network(LAN), a wireless network, a public telephone network, an intranet, andso on. The network may be configured to include multiple sub-networks.

The following discussion describes techniques that may be implementedusing the previously described systems and devices. Aspects of each ofthe procedures may be implemented in hardware, firmware, or software, ora combination thereof. The procedures are shown as a set of blocks thatspecify operations performed by one or more devices and are notnecessarily limited to the orders shown for performing the operations bythe respective blocks.

Exemplary Procedures

The following discussion describes techniques that may be implementedutilizing the previously described systems and devices. Aspects of eachof the procedures may be implemented in hardware, firmware, or software,or a combination thereof. The procedures are shown as a set of blocksthat specify operations performed by one or more devices and are notnecessarily limited to the orders shown for performing the operations bythe respective blocks. A variety of other examples are alsocontemplated.

FIG. 3 discusses exemplary procedures for identifying active audio inputclients in media sessions. For example, the techniques may be used in aconference call or a media conference in which some clients lack videocapability and so on.

In implementations, a media server, serving as a host, or central point,may determine 302 audio input clients with respect to the input providedby each active client. For example, a determination may be made as partof mixing and/or switching audio client input. Thus, Client A may beassigned as the paramount active client until a different clientprovides audio input. In another example, Client A may be selected ifClient A and Client E are contributing but Client A's audio has a higherenergy level. Client audio may have a higher energy level if theparticipant associated with the client is talking in a loud voice or istalking in a more continuous fashion such as if the client is dominatingthe audio input.

An audio input client may be identified as the “top” client if theclient is currently active, dominates the conversation and so on. InRTP/RTCP systems functioning in accordance with the present techniques,the media server may obtain the client input streams and associated RTCPpackets (e.g., the RTCP packets sent from a client) including a SSRCmapped to a CNAME 304 for the particular client generating the streamincluding the audio content. For example, the media server may obtainthe SSRC and CNAME for the client. The CNAME identifying the client inconjunction with the SSRC. The media server may order 306 the inputclient SSRCs according to which clients are currently providing audioinput, dominating the conversation, and so on. For example, the mediaserver may order the active clients SSRC identifiers descending from thecurrent active “speaker” e.g., the active client providing input. Ininstances, RTP may permit identification of 15 active speakers using athirty-two bit identifier per active client included in the CRSC.

The media server may associate an identifier with the audio inputclient. For instance, the media server may obtain the SSRC and CNAMEfrom an audio input client RTCP packet. The SSRC may be used to identifythe audio input client in the CRSC field included in the media serveroutput stream.

The clients may receive/associate other data with the audio inputclient. For example, a receiving client (a listening client or a clientin the media event) may have human understandable information associatedwith the CNAME. For example, a client may have a picture of theparticipant, the participant's name and so on (which is associated withthe client CNAME/SSRC).

The ordered audio input client identifiers may be inserted 308 into alist in the packet header. For example, if Clients “A” and “E” areproviding audio input (with Client A being the current active client),the CSRC field in the RTP header may include the SSRCs with the SSRC forClient “A” commencing the list. In this way a listening client (whichmay include an audio input client which receives audio input fromanother active client) may be informed of the speaker's identity insidethe content stream. In another example, the order of the audio inputclients in the list may be based, at least in part, on which audio inputclient is dominating the media session. Dominating considerations mayinclude energy level of the audio input, duration of the input, durationof silence periods, packet size, and so on. For example, the list maycommence with Client A because Client A is currently active and theClient A send stream indicates a high energy level in comparison to oneor more other audio input clients.

The media server may send 310 to a listening client (a session client)the SSRC and CNAME in the media server send stream(s) (such as in RTCPpackets sent in conjunction with content transport). The SSRC, for theaudio input clients, may also be located the CSRC field in the datastream packet header in RTP packets. For example, if in a five clientmedia event, three participants are speaking, the client SSRC and CNAMEassociated with the audio input clients may be included in the mediaserver RTCP packets (sent to the listening clients) associated with theRTP packets communicating the audio content. In this way, the mediaserver may send the clients the SSRC and the CNAME identifying theactive audio clients. Thus, a listening client may identify theoriginating source of the audio content with reference to the SSRC(s)and CNAME(s) in the RTP packet. A client SSRC may be updated if theclient SSRC collides with the SSRC issued to another client, or if theclient changes a source transport address for another reason. TheSSRC(s) and CNAME(s) may be stored in local memory 312 so that alistening client may access the information throughout the media event.

FIG. 4 exemplary techniques for identifying active clients in a mediaconference are discussed. For instance, the present techniques may beused during a media conference in which some of the clients lack video,or may be used in an audio conference call.

In the present implementations, a media server may receive 402 activeclient input (audio content) as well as identifiers from the activeclients. For example, a client contributing to an audio conference maysend a SSRC and a CNAME which identify the client. For example, the SSRCmay be included in the data stream in a RTP packet header and in a RTCPpacket along with the CNAME.

An ordered 404 list of one or more active clients within a conferencemay be generated. For example, a media server mixing/switching audioinput stream may arrange a list of active client (SSRC identifiers inRTP/RTCP), or those clients providing input into the conference orsession. For example, the media server is an audio/video mixing server(AVMCU) which obtains the SSRC identification from an active client sendstream which in-turn may include a data portion and an associatedsignaling portion. The AVMCU may then determine the relative arrangementof the active clients SSRCs or other identifier for the client withinthe session. The SSRC may be identified from an RTCP report which maymap to the client CNAME. For example, the ranking may be based on whichclient is presently active. In other implementations, factors such asthe energy level, the number of data packets provided, the duration ofthe silence periods, packet size and so on may be taken into account.For example, the ordered list may commence with an active client whichmay dominate the session because of the number of packets provided,while a second contemporaneously active client is assigned a lesserrelative status.

The ordered list may be inserted 406 in to the CSRC list field includedin packet headers within the media server send data stream flows. Forexample, the media server output includes the audio provided by anactive client, a CSRC field with the ordered list of SSRC identifiersfor the active clients. As a result, a listening client, i.e., a clientreceiving the audio content stream, may be informed as to which clientsare active, and the relative relationship of the active clients.Additionally, the SSRC and the CNAME may be included in media serversend RTCP packets.

The SSRCs may be associated 408 with the CNAME of the active audioclient. For example, a media server may send a RTCP packet whichincludes the client CNAME related to an SSRC included in the CRSC fieldin the RTP packet header. The CNAME may be obtained from the RTCPpackets.

Human understandable information may be associated with the CNAME and/orthe audio input client SSRC as well. For example, a picture or a namemay be associated with the client CNAME so that a participant's pictureor name appears when the associated client is providing audio content.This information may be communicated within the conference or a clientmay input this human understandable information.

In further implementations a GRUU may be associated with the SSRC forthe active client. In some situations in which a client is active, butother clients are not active, the media server may provide 410 anindication to the active client so that the active client is notifiedthat no other client is active, although the active client send streamis not returned to the active client. In this manner, the active clientis made aware that the participant is not “talking over” anotherparticipant.

While RTP and RTCP are discussed the techniques and implementations ofthe present disclosure may be applied to other protocols data transportmechanisms.

Conclusion

Although the invention has been described in language specific tostructural features and/or methodological acts, it is to be understoodthat the invention defined in the appended claims is not necessarilylimited to the specific features or acts described. Rather, the specificfeatures and acts are disclosed as exemplary forms of implementing theclaimed invention.

1. A computer implemented method comprising: Receiving a first input from a first individual audio input client, the first input indicating that the first individual audio input client is a first active participant in an audio event, wherein the audio event comprises active and inactive participants; receiving a second input from a second individual audio input client, the second input indicating that the second individual audio input client is a second active participant in the audio event; receiving a third input from a third individual audio input client, the third input indicating that the third individual audio input client is a third active participant in the audio event; associating a first identifier with the first individual audio input client, a second identifier with the second individual audio input client, and a third identifier with the third individual audio input client; upon receiving the first, second, and third input, determining that the first individual audio input client is a dominant speaker over the second individual audio input client; ordering the first identifier above the second identifier and the third identifier in a real-time transport protocol (RTP) contributing source list (CSRC) based on the determination that the first individual audio input client active participant is the dominant speaker over the second and third individual audio input client active participants, wherein the first identifier is placed at the top of the CSRC list to identify a relative relationship of the first, second, and third active clients, and wherein inactive participants are not included in the list; and inserting the list of the ordered first identifier, the second identifier and third identifier into a packet header.
 2. The computer implemented method as described in claim 1, wherein ordering is determined by a host mixing audio streams such that the list descends from a current active audio input client.
 3. The computer implemented method as described in claim 1, further comprising sending a canonical name (CNAME) and a synchronization source (SSRC) identification mapped to the CNAME for the individual client.
 4. The computer implemented method as described in claim 3, wherein the CNAME and associated SSRC are obtained from a real-time control protocol (RTCP) record for the individual client.
 5. The computer implemented method as described in claim 4, wherein the CNAME and associated SSRC are sent in a RTCP packet to a listening client.
 6. The computer implemented method as described in claim 1, further comprising storing the CNAME and SSRC in a listening client local memory.
 7. The computer implemented method as described in claim 1, wherein a dominant client is determined based on at least one of energy level, duration of the silence periods, duration or packet size.
 8. The computer implemented as described in claim 1, further comprising updating the synchronization source (SSRC) identification with a client canonical name (CNAME) if the client changes source transport address within a session.
 9. One or more computer-readable memory comprising computer executable instructions that, when executed, direct a computing system to: receive a first input from a first individual audio input client, the first input indicating that the first individual audio input client is a first active participant in an audio event, wherein the audio event comprises active and inactive participants; receive a second input from a second individual audio input client, the second input indicating that the second individual audio input client is a second active participant in the audio event; receive a third input from a third individual audio input client, the third input indicating that the third individual audio input client is a third active participant in the audio event associate a first identifier with the first individual audio input client, a second identifier with the second individual audio input client, and a third identifier with the third individual audio input client, wherein each individual audio input client is associated with a canonical name (CNAME) and a synchronization source (SSRC) identification; upon receiving the first, second, and third input, determine that the first individual audio input client is a dominant speaker over the second and third individual audio input clients; order a list of one or more active individual audio input clients in a conference based on the determination that first individual audio input client active participant is the dominant speaker over the second and third individual audio input client active participants, such that the first identifier is placed above the second and third identifiers in the list to identify a relative relationship of the first, second, and third active clients, and wherein inactive participants are not included in the list; and insert the ordered list into a real-time protocol (RTP) contributing source list (CSRC) field in one or more audio streams.
 10. The one or more computer-readable memory as described in claim 9, wherein the ordered list commences with a dominant active client.
 11. The one or more computer-readable memory as described in claim 10, further comprising determine the dominant client based on at least one of energy level, duration of the silence periods, duration or packet size.
 12. The one or more computer-readable memory as described in claim 9, wherein the SSRC identification is mapped to the CNAME obtained from a control packet for one or more received audio streams.
 13. The one or more computer-readable memory as described in claim 12, wherein the control packet is real-time control protocol (RTCP) compliant.
 14. The one or more computer-readable memory as described in claim 13, wherein the SSRC and the CNAME are included in a real-time control protocol (R TCP) packet.
 15. The one or more computer-readable memory as described in claim 9, further comprising provide a dominant active audio client, included in the one or more active clients, an indication that no other audio client is active.
 16. A system comprising: a media server for performing the following: receiving a first input from a first individual audio input client, the first input indicating that the first individual audio input client is a first active participant in an audio event, wherein the audio event comprises active and inactive participants; receiving a second input from a second individual audio input client, the second input indicating that the second individual audio input client is a second active participant in the audio event; receiving a third input from a third individual audio input client, the third input indicating that the third individual audio input client is a third active participant in the audio event; associating a first identifier with the first individual audio input client, a second identifier with the second individual audio input client, and a third identifier with the third individual audio input client; upon receiving the first, second, and third input, determining that the first individual audio input client is a dominant speaker over the second and third individual audio input clients; ordering the first identifier above the second and third identifiers in a real-time transport protocol (RTP) contributing source list (CSRC) based on the determination that the first individual audio input client active participant is the dominant speaker over the second and third individual audio input client active participants, wherein the first identifier is placed at the top of the list, and wherein inactive participants are not included in the list to identify a relative relationship of the first, second, and third active clients; and inserting the list of the ordered first identifier, the second identifier and third identifier into a packet header.
 17. The system as described in claim 16, wherein the ordered list indicates a dominant client based on at least one of an energy level, duration of the silence periods, a duration, or a packet size associated with a media stream received from the dominant client.
 18. The system as described in claim 16, wherein the media server sends to clients receiving send media streams active client identifiers including the canonical name (CNAME) and the synchronization source (SSRC) identification mapped to the CNAME for the active client in a real-time control protocol (RTCP) packet. 